Automatically adjustable trimming mechanism

ABSTRACT

This disclosure relates to an automatically adjustable trimming mechanism for use in association with sewing machines and includes a knife for trimming material being sewn with the knife being shiftable transversely of the direction of material feed for selectively varying the spacing of the trimmed edge of material from the needle of the sewing machine. A simple linkage is provided for shifting the knife and this linkage is actuated by power means which is remotely controllable. The controls for the power means may be mounted on a treadle for controlling the operation of the sewing machine wherein a single treadle may be utilized for controlling the sewing machine and the shifting of the position of the knife.

United States Patent 1 1 Davis et al.

[ June 12, 1973 AUTOMATICALLY ADJUSTABLE TRIMMING MECHANISM [7 5] Inventors: Farris L. Davis, Fayetteville; Daniel D. Brown, Springdale, both of Ark.

[73] Assignee: Union Special Machine Company,

Chicago, Ill.

[22] Filed: v Apr. 13, 1971 21 Appl. 133,683

[52 us. 01. 112/126 [51] Int. Cl D051) 37/02 v [58] Field of Search 112/123, 125, 126,

[56] References Cited i i I 2;

UNITED STATES PATENTS 4 3,125,048 3/1964 Tringali 112/123 2,868,147 1/1959 Wood l12/l26X 2,427,609 9/1947 Knaus 112/126 3,425,373 2/1969 Miller et al. 112/130 Primary Examiner-H. Hampton Hunter Attorney-Diller, Brown, Ramik & Holt [57] ABSTRACT This disclosure relates to an automatically adjustable trimming mechanism for use in association with sewing machines and includes a knife for trimming material being sewn with the knife being shiftable transversely of the direction of material feed for selectively varying the spacing of the trimmed edge of material from the needle of the sewing machine. A simple linkage is provided for shifting the knife and this linkage is actuated by power means which is remotely controllable. The controls for the power means may be mounted on a treadle for controlling the operation of the sewing ma- "chine wherein a single treadle may be utilized for controlling the sewing machine and the shifting of the position of the knife.

10 Claims, 4 Drawing Figures AUTOMATICALLY ADJUSTABLE TRIMMING MECHANISM This invention relates in general to new and useful improvements in sewing mechanisms, and more particularly to an automatically adjustable trimming mechanism for sewing machines and like structure.

BACKGROUND OF THE INVENTION It is conventional to provide a sewing machine with an adjustable trimming mechanism which will trim material in advance of being sewn. Such trimming mechanism includes blades which are shiftable transversely of the direction of material feed for selectively trimming material at different spacings from the needle of the sewing machine so as to produce seams of different widths.

In the past, the mechanism for shifting the position of the trimming mechanism has been directly controlled by the machine operator and a separate foot or knee treadle has been required to change the position of the trimming mechanism.

Adjustable trimming mechanism of the type identified above is disclosed-in the US. Pat. to Tringali No. 3,125,048 issued Mar. 17, 1964. As will be apparent from that patent, the knife shifting mechanism requires the provision of a separate actuator which must be manipulated by the machine operator in order to-efiect the shifting of the position of the trimming mechanism.

A further undesirable feature of existing trimming mechanism is that the machine operator, because of the direct connection between the actuator and the shifting mechanism, can physically overpower the knife shifting mechanism, causing damage to the mechanism or the knives.

SUMMARY OF THE INVENTION In accordance with this invention, the knife shifting mechanism previously utilized has been simplified to include a simple lever which is positioned by power means relative to an adjustable stop in a relationship wherein the power means'cannot be actuated to physically overpower the knife shifting mechanism, whereby accidental damage to the shifting mechanism or the knives is prevented.

It is fully acknowledged that it is well known to utilize a solenoid to move a trimmer knife in specific mechanism. This is taught in the US. Pat. to Wood No. 2,868,147, issued Jan. 13, 1959. However, this patent merely discloses a conventional type solenoid actuatorhaving a controlled effective length at actuation.

In accordance with this invention prior required relatively complicated linkage is replaced by a simple single lever which has one end thereof in position for shifting a knife support and the other end thereof disposed between a power unit and an adjustable stop with the power unit being operable to move the lever only that distance which will be permitted by the adjustable stop and wherein the force exerted by the power unit beyond that required to effect shifting of the knife and its support is absorbed by-the stop.

Still another feature of this invention is the provision of a simple control for the power unit remote from the power unit with the control being of such a nature wherein it may be mounted on a treadle for. controlling the operation of a sewing machine in the normal manner and wherein the control mechanism for the power unit is actuated only upon the depressing of the treadle upon a predetermined amount and wherein the control mechanism for the power unit may be selectively actuated without in any way interferring with the normal operation of the sewing machine.

With the above and other objects in view that will hereinafter appear, the nature of the invention will be more clearly understood by reference to the following detailed description, the appended claims and the several views illustrated in the accompanying drawings:

In the drawings:

FIG. 1 is an elevational view showing generally the over-all sewing machine mechanism including the automatic knife shifting mechanism.

FIG. 2 is a fragmentary plan view of the sewing machine of FIG. 1 with parts broken away and shown in section and shows the specific details of the knife shifting mechanism.

FIG. 3 is a fragmentary elevational view from the front side of FIG. 2 showing only the essential elements of the automatic knife shifting mechanism.

FIG. 4 is a schematic view of the control system for operating the knife shifting mechanism.

Referring now to the drawings in detail, it will be seen that there is illustrated in FIG. 1 conventional sewing machine structure which includes a table 10 mounted at an elevated position with respect to a supporting surface 11 by means of suitable standards 12. The table 10 has mounted thereon in a conventional manner, a sewing machine which is generally identified by the numeral l3 and which is of a conventional construction. The illustrated sewing machine is of the overedge stitch forming type, but the invention is in no way limited to such a sewing machine.

Actuation of the sewing machine 13 is controlled at least in part by means of a treadle 14 which is suitably mounted relative to the table 10 on a generally horizontal pivot shaft 15. The treadle 14 is connected to conventional sewing machine control structure 16 by means of a link 17. The afore-described structural components are all conventional and in of themselves in no way form a part of this invention.

Referring now to FIG. 2, it will be seen that the sewing machine 13 includes a frame 18 which includes wall portions 20,21 in which there is mounted for both rocking movement and axial shifting movement a rock shaft 22. The rock shaft 22 is provided at the left end thereof with an upper knife carrying arm 23 which extends therefrom generally parallel to the frame portion 20 and which has secured thereto for generally vertically reciprocating movement an upper knife 24.

The end of the rock shaft 22 remote from the arm 23 is provided with an adjustably mounted link 25 to which a pitman 26 is connected in a conventional manner. The pitman 26, in turn, is carried by a crankshaft 27 of the sewing machine 13, the crankshaft 27 being driven in a conventional manner. It will be readily apparent from the foregoing that when the crankshaft 27 is rotating, the pitman 26 will function, through the link 25, to rock the shaft 22 through a suitable are, thus moving the upper knife 24 substantially vertically through its trimming stroke. The upper knife 24 cooperates with a lower knife 28 which is stationarily, but adjustably, secured to a lower knife holder 30. The knife holder 30 is slidably mounted in a block 31 fixed to the machine frame 18. A guiding sleeve 32 is clamped by means of a shoulder screw 33 to a boss 34 extending from the block 31. The sleeve 32 passes through a hole 35 in a face 36 of the lower knife holder 30. A spring 37 and a spring holder 38 are also carried by the shoulder screw 33.

With particular reference to FIG. 2, it will be seen that the lower knife 28 is biased towards the right by a spring 40 mounted in the lower knife holder 30 and held in a compressed relation by means of a laterally extending arm 41 which is removably secured to the block 31 by means of a screw 42. At this time, it is to be noted that the spring 37 functions to help keep'the lower knife holder 28 from binding as it is being pushed back to its original position in a manner to be described hereinafter.

As is clearly shown in FIG. 2, the upper knife 24 together with the knife support arm 23 and the rock shaft 22 are constantly urged to the left by a spring 43 which is mounted on the rock shaft between the frame portions 20,21. The spring 43 reacts at one end against a collar 44 adjustably mounted on the rock shaft 22 and at the opposite end on the frame portion 21.

The end portion of the knife support arm 23 remote from the rock shaft 22 is in constant engagement with a guide block 45. The guide block 45 is carried by a sleeve 46 which is slidably mounted within a bore 47 formed in the frame portion 20. A spring 48 is telescoped within the sleeve 46 and reacts against the sleeve and the frame portion 20 to constantly urge the guide block 45 to the left. The guide block 45 is prevented from rotating by means of an elongated member 50 which may be in the form of a tube which functions as a thread guide. The member 50 will be suitably anchored against turning in a manner not illustrated herein.

It is to be understood that in the normal position of the upper knife 24 and the support am 23, material being sewn will be trimmed so as to extend a certain distance to the right of the sewing machine needle (not shown) so as to define the width of the seam which is being formed. When it is desired to increase the width of the trimmed edge extending beyond the sewing machine needle, the upper knife support arm 23 is moved to the right against the resistance of the springs 43 and 48. At this time, due to the compression of the spring 40, the lower knife 28 is moved to the right in a like manner, the spring 40 overpowering the spring 37.

When the pressure on the upper knife support arm 23 urging the same to the right is removed, the springs 43 and 48 will automatically return the support arm 23 to its original position. At the same time, the lower knife 28 will be moved back to its original cooperating position with the upper knife 24 notwithstanding the resistance of the spring 40. The spring 37 willassist in this movement of the lower knife 28.

In accordance with this invention, simple means for automatically positioning the knife support arm 23 are provided, the means including a special link or lever which is generally identified by the numeral 51. The link 51 includes an elongated arm 52 which is joined to a central portion 53. Extending from the central por-i tion 53 in generally the opposite direction from the arm 52 and in angular relation to the arm 52 is an arm 54. The arm 54, in turn, has a depending portion 55 which engages the upper knife support arm 23 substantially in alignment with the rock shaft 22. The central portion 53 of the link 51 is pivotally mounted on the machine frame 18 by means ofa shoulder screw'56. The link 51,

which also may be considered to be an upper knife shifting arm, has the arm 52 thereof disposed in overlying relation to a bracket 57 which includes a base flange 58 adjustably secured to the sewing table 10 by means of fasteners 60. The bracket 57 also includes an upstanding leg 61 (FIG. 3) which terminates at its upper end into a horizontal portion 62. The horizontal portion 62 terminates in an upstanding flange 63.

A suitable power unit 64 is seated on and secured to the horizontal portion 62 of the bracket 57 and has a plunger 65 which is engageable with the arm 52. In the preferred-embodiment of the invention, the power unit 64 is an extensible air cylinder, but could be in the form of any type-of extensible fluid motor or a linearly actuatable electric motor such as a solenoid.

The flange 63 is provided with a stop screw 66 which substantially opposes the plunger 65 and is adjustably threadedly carried by the flange 63. The adjustable stop screw 66 is provided with a locking nut 67 to lock it in an adjusted position. If desired, the stop screw 66 may be provided with an enlarged head 68 for engagement with the arm 52 with the head 68 being formed of a suitable shock absorbing material.

It will be readily apparent from FIG. 2 that when the plunger 65 is moved to the left, it will pivot the link 51 in a counterclockwise direction and the arm portion 55 thereof will move to the right, moving the upper knife support arm 23 to the right against the resistance of the springs 43,48. The amount of movement of the arm 52 will obviously be controlled by the position of the adjustable stop screw 66, thereby limiting the pivoting of the link 52 by the power unit 64. In this manner, accurate positioning of the upper knife 24 in its adjusted position is assured. In a like manner, overpowering of any component of the knife mounting or the link 51 is prevented inasmuch as any excess force exerted by the power unit 64 on the link 51 is directly absorbed by the stop screw 66 as opposed to applying a bending or twisting force on the link 51 and the mounting components for the knives 24, 28.

Referring now to FIG. 1 in particular, it will be seen that there is mounted in any desired operable relation with respect to the treadle 14 a control member 70 for thepower unit 64. When the power unit 64 is in the form of an extensible air motor, the control unit 70 will be in the form of'an air switch or valve. An air line 71 connects the valve 70 with the air motor 64 to effect the actuation thereof.

\ Referring now to FIG. 4, it will be seen that when the power unit 64 is in the form of an air motor, the control system will also include a compressed air conduit 72 which leads from an air source (not shown) through a conventional filter 73 to a pressure regulator 74. Air passing through the pressure regulator 74, in turn, passes through a conventional air line lubricator 75 and into the control valve 70 through a conduit or air line 76.

OPERATION When the operator wishes to shift the knife mechanism, the operator depresses the treadle 14 fully, thereby activating the air switch or valve 70 to direct air into the power unit 64. The plunger 65 extends to the left to pivot the link 51 in a counterclockwise direction until the arm 52 of the link 51 contacts the stop screw 66 which has been set for the width of the seam that is desired. The arm portion 55 of the link 51 also pivots in a counterclockwise direction, thereby shifting the upper knife 24 to the right with the lower knife 28 following it by the action of the spring 40. When the desired length of increased seam width has been reached, the operator merely releases the treadle 14 enough to de-activate the air switch 70, thus stopping the air flow through the air cylinder 64 and allowing the trimmer mechanism to return to its original position.

Although only a preferred embodiment of the invention has been specifically illustrated and described herein, it is to be understood that minor variations may be made in the means for automatically adjusting the position of the trimming mechanism without departing from the spirit and scope of the invention, as defined by the appended claims.

We claim:

1. In combination with a sewing machine, an automatically adjustable trimming mechanism having a normally fixed position and being shiftable relative to the path of material through said sewing machine to vary the effective position thereof, said trimming assembly including a blade support, linkage connected to said blade support for effecting controlled shifting of said blade support to a preselected second operating position, power means for shifting said linkage said power means having an effective stroke greater than that required to shift said linkage for the shifting of said blade support to said preselected second operating position, and adjustable stop means opposing said power means for directly limiting the movement of said linkage and thus said blade support without stressing said linkage and said blade support.

. 2. The combination of claim 1 wherein foot actuated control means are provided for said power means remote from said power means.

3. The combination of claim 2 wherein a single treadle is provided for actuating said sewing machine and said foot actuated control means.

4. The combination of claim 1 wherein said power means are of the fluid energized type and have remotely disposed control means.

5. The combination of claim 1 wherein said trimming mechanism is of the type for controlling seam width.

6. The combination of claim 1 wherein said trimming mechanism is of the type for controlling seam width, and said sewing machine is of the overedge seam forming type.

7. The combination of claim 1 wherein said linkage consists of a single link having a pivotally mounted intermediate portion and remote end portions for engagement by said power means and with said blade support.

8. The combination of claim 7 wherein said power means and said adjustable stop are carried by a single separate bracket with one of said link remote end portions being disposed between said power means and said stop means.

9. The combination of claim 1 wherein said sewing machine includes a driven rock shaft, said blade support is of the reciprocating type, and said blade support is carried by said rock shaft.

10. The combination of claim 1 wherein said sewing machine includes a driven rock shaft, said blade is of the reciprocating type, said blade support is carried by said rock shaft, and means mounting said rock shaft for axial movement by said linkage. 

1. In combination with a sewing machine, an automatically adjustable trimming mechanism having a normally fixed position and being shiftable relative to the path of material through said sewing machine to vary the effective position thereof, said trimming assembly including a blade support, linkage connected to said blade support for effecting controlled shifting of said blade support to a preselEcted second operating position, power means for shifting said linkage said power means having an effective stroke greater than that required to shift said linkage for the shifting of said blade support to said preselected second operating position, and adjustable stop means opposing said power means for directly limiting the movement of said linkage and thus said blade support without stressing said linkage and said blade support.
 2. The combination of claim 1 wherein foot actuated control means are provided for said power means remote from said power means.
 3. The combination of claim 2 wherein a single treadle is provided for actuating said sewing machine and said foot actuated control means.
 4. The combination of claim 1 wherein said power means are of the fluid energized type and have remotely disposed control means.
 5. The combination of claim 1 wherein said trimming mechanism is of the type for controlling seam width.
 6. The combination of claim 1 wherein said trimming mechanism is of the type for controlling seam width, and said sewing machine is of the overedge seam forming type.
 7. The combination of claim 1 wherein said linkage consists of a single link having a pivotally mounted intermediate portion and remote end portions for engagement by said power means and with said blade support.
 8. The combination of claim 7 wherein said power means and said adjustable stop are carried by a single separate bracket with one of said link remote end portions being disposed between said power means and said stop means.
 9. The combination of claim 1 wherein said sewing machine includes a driven rock shaft, said blade support is of the reciprocating type, and said blade support is carried by said rock shaft.
 10. The combination of claim 1 wherein said sewing machine includes a driven rock shaft, said blade is of the reciprocating type, said blade support is carried by said rock shaft, and means mounting said rock shaft for axial movement by said linkage. 